Bone loss is commonly associated with several diseases, including osteolysis, metastatic lesions, and osteoporosis. Though bone loss often refers to the dissolution of bone secondary to a variety of medical conditions, the term osteolysis generally refers to a bone resorption problem common to artificial joint replacements such as hip replacements, knee replacements, and shoulder replacements. Osteolysis often occurs in the bone adjacent to an orthopedic implant, such as a hip or knee implant. As the body attempts to clean the orthopedic implant wear particles from the surrounding bone, an autoimmune reaction may be triggered. This autoimmune reaction causes the resorption of living bone tissue in addition to resorption of the wear particles. This bone resorption forms voids or osteolytic lesions in the bone. Osteolytic lesions are typically soft and spongy, and are unsupportive of orthopedic implants. They may be amorphous and have indeterminate boundaries as viewed on radiographic images. An osteolytic lesion can cause a well-fixed implant to loosen. To treat osteolysis in the area of an implant, it is often necessary to conduct a revision surgery in which the old implant is removed, the lesion is debrided, and a larger revision implant is inserted.
In addition to osteolytic lesions secondary to implant reactions, another common form of osteolytic lesions are “punched out” osteolytic lesions secondary to metastatic cancer. “Punched-out” osteolytic lesions are characteristic of metastatic lung and breast cancers and multiple myeloma.
Both types of osteolytic lesions can trigger a host of serious medical problems in patients, including severe pain, bone fractures, life-threatening electrolyte imbalances, and nerve compression syndromes. One of the treatments for alleviating the symptoms of osteolytic lesions involves clearing the lesion of cellular debris and filling it with biomaterial or bone cement. Because patients with osteolytic lesions are typically older, and often suffer from various other significant health complications, many of these individuals are unable to tolerate invasive surgery. Therefore, in an effort to more effectively and directly treat osteolytic lesions, minimally invasive procedures may be utilized to repair the bone by injecting an appropriate amount of flowable reinforcing material into the osteolytic lesion. Shortly after injection, the filling material hardens, thereby filling the lesion and supporting the bone internally.
In contrast to an open procedure for the same purpose, a minimally invasive, percutaneous procedure will generally be less traumatic to the patient and result in a reduced recovery period. However, minimally invasive procedures present numerous challenges. For example, conventional single balloon catheters used to compact bone and create cavities for reinforcing material are too small for use with the larger osteolytic lesions. Further, conventional single balloon catheters do not allow for versatile control of balloon inflation to accommodate the amorphous nature of osteolytic lesions. Accordingly, there exists a need for instrumentation and techniques that facilitate the more effective and efficient treatment of bone dissolution using minimally invasive procedures.